A modular multilevel space vector modulation for photovoltaic quasi-Z-source cascade multilevel inverter

Abstract

A quasi-Z-source cascade multilevel inverter (qZSCMLI) based photovoltaic (PV) power system yields high-quality output voltage with power switching at low frequency similar to traditional cascade multilevel inverter (CMLI), and boosts PV panel voltages by quasi-Z-source shoot-through duty ratio control. A two-level space vector modulation (SVM) based multilevel SVM for qZS-CMLI is presented to independently control the shoot-through duty ratio of respective H-bridge inverter (HBI) cells, with the aim to compensate the unequal voltages of separate PV modules. Moreover, it can be modularly extended to any cascaded levels. Simulation and experimental results demonstrate the validness of the proposed scheme.